Crato Formation

Crato Formation
Stratigraphic range: Latest Aptian ~115–113 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Santana Group
Sub-units	Nova Olinda Member
Underlies	Romualdo & Ipubi Formations
Overlies	Barbalha Formation
Lithology
Primary	Mudstone, limestone
Other	Siltstone
Location
Coordinates	7°06′S 39°42′W / 7.1°S 39.7°W / -7.1; -39.7
Approximate paleocoordinates	8°36′S 8°00′W / 8.6°S 8.0°W / -8.6; -8.0
Region	Ceará,  Pernambuco
Country	Brazil
Extent	Araripe Basin
Type section
Named for	Crato, Ceará
Extent of the Santana Group, to which the Crato Formation belongs, in blue

The Crato Formation is a geologic formation of Early Cretaceous (Aptian) age in northeastern Brazil's Araripe Basin. It is an important Lagerstätte (undisturbed fossil accumulation) for palaeontologists. The strata were laid down mostly during the Aptian age, about 113 million years ago. It thought to have been deposited in a semi-arid lacustrine wetland environment.^[1]

The Crato Formation earns the designation of Lagerstätte due to an exceedingly well preserved and diverse fossil faunal assemblage. Some 25 species of fossil fishes are often found with stomach contents preserved, enabling paleontologists to study predator-prey relationships in this ecosystem. There are also fine examples of pterosaurs, reptiles and amphibians, invertebrates (particularly insects), and plants. Even dinosaurs are represented: a new maniraptor was described in 1996. The unusual taphonomy of the site resulted in limestone accretions that formed nodules around dead organisms, preserving even soft parts of their anatomy.